Information retrieval apparatus

ABSTRACT

Information retrieval apparatus, particularly for locating a desired frame on a microfilm strip, comprises a photoelectric transducer for detecting the passage therepast of markers on the film strip, each marker being associated with a particular frame, a counter for counting the corresponding signals produced by the transducer, storage means for storing the serial number of a frame to be brought to a reading position, comparing means for continually comparing the count of the counter with the stored serial number, and means for arresting the film movement when the comparison shows equality. The storage means also includes means for storing the serial number of the frame initially in the reading position, this number being also fed into the counting means to provide a datum count. The apparatus also includes means for sensing that the desired frame is approaching the reading position and for slowing down the film so as to avoid overshoot when the film is finally arrested. The apparatus can drive the film in either direction to locate the desired frame and, when one desired frame has been located, a further desired frame can be located without having to rewind the film to a datum position.

United States Patent Douglas L. Steggall London, England [21] Appl.No.767,608

[72] lnventor [22] Filed Oct. 15, 1968 [45 Patented Mar. 30, 1971 [73]Assignee Selectro-Micro Company Limited London, England [32] PriorityJuly 3, 1968, July 12, 1968 [3 3] I Great Britain [31] 31,671/68 and33,307/68 [54] INFORMATION RETRIEVAL APPARATUS Primary ExaminerRichardA. Schacher Attorney-Smith, Michael, Bradford & Gardiner ABSTRACT:Information retrieval apparatus, particularly for locating a desiredframe on a microfilm strip, comprises a photoelectric transducer fordetecting the passage therepast of markers on the film strip, eachmarker being associated with a particular frame, a counter for countingthe corresponding signals produced by the transducer, storage means forstoring the serial number of a frame to be brought to a readingposition, comparing means for continually comparing the count of thecounter with the stored serial number, and means for arresting the filmmovement when the comparison shows equality. The storage means alsoincludes means for storing the serial number of the frame initially inthe reading position, this number being also fed into the counting meansto provide a datum count. The apparatus also includes means for sensingthat the desired frame is approaching the reading position and forslowing down the film so as to avoid overshoot when the film is finallyarrested. The apparatus can drive the film in either direction to locatethe desired frame and, when one desired frame has been located, afurther desired frame can be located without having to rewind the filmto a datum position.

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1. In apparatus having transport mechanism for driving, along apredetermined path, a longitudinally movable recording medium having aplurality of longitudinally arranged areas in which information can berecorded and a respective marker associated with each area, andtransducer means adjacent the said path and producing a respectiveelectrical signal in response to the movement of each marker therepast,the improvement comprising: counting means connected to count theelectrical signals; first and second stores, each store having n decaderegions, each decade region having a plurality of storage locations;first routing means operative, when activated, for accessing the decaderegions of the first store in turn; second routing means operative, whenactivated, for accessing the decade regions of the second store in turn;means operative to activate each routing means; a decade set of keyingmeans; a decade set of switch means connected to be operated by thekeying means; power supply means for energizing the switch means; aplurality of first output connections connecting the switch means to thefirst and second routing means, one particular first output connectionbeing energized by the power supply means according to which of thekeying means is operated whereby to store a corresponding digit in theparticular store region which is accessed at that time by the routingmeans such that by appropriate selective operation of the keying meansas each routing means is activated while the recording medium isstationary the digits of a first number identifying the particularmarker in a reference position in the said path are respectively storesin the decade regions of the first store and the digits of a secondnumber identifying the particular marker to be brought, by appropriatemovement of the recording medium, to the reference position in the saidpath are respectively stored in the decade regions of the second store;n further decade sets of switch means, each decade set being ganged foroperation by the keying means; n input connections respectivelyassociated with the further decade sets of swiTch means, each inputconnection being common with all the switch means of the respectivefurther decade set; n sets of second output connections, each secondoutput connection of a set being connected to a respective switch meansof a respective set of the further switch means; means operative insynchronism with the said second routing means to serially energize then input connections, whereby, as each input connection is energized, aparticular one of the corresponding set of second output connections isenergized according to the setting of the keying means; means connectingthe second output connections to the counting means whereby theparticular second connection of each set of the second outputconnections sets into the counting means a different decade of the firstnumber so as to count up the counting means by a count correspondingwith the said first number while the recording medium is stationary; andcomparing means connected to the counting means and the stores andoperative to compare the instantaneous count of the counting means withthe said second number as the recording medium moves along the saidpath, and arranged to produce a transport mechanism-arresting signalwhen the said count corresponds with the second number.
 2. In apparatushaving variable speed transport mechanism for driving, along apredetermined path, a longitudinally movable recording medium having aplurality of longitudinally arranged areas in which information can berecorded and a respective marker associated with each area, andtransducer means mounted and operative to produce a respectiveelectrical signal in response to the movement of each marker therepast,the improvement comprising: counting means connected to count the numberof electrical signals produced; storage means operative to store anidentifying number identifying a particular marker which is to bepositioned, by appropriate movement of the recording medium, in areference position in the said path; means operative to add apredetermined number to the count of the counting means so that, as therecording medium moves along the said path, the instantaneous count ofthe counting means is in excess, by the amount of the said predeterminednumber, of the number of electrical signals counted; comparing meansconnected to the counting means and the storage means and operative tocompare the instantaneous count of the counting means with the saididentifying number in the storage means; first control means responsiveto the comparing means and arranged to produce a transport mechanismspeed reducing signal when the instantaneous count of the counting meanscorresponds with the identifying number; and second control meansoperative to produce a transport mechanism arresting signal when thenumber of electrical signals produced by the transducing means afteroccurrence of the said speed reducing signal becomes equal to the saidpredetermined number.
 3. Apparatus according to claim 2, in which thecounting means includes an auxiliary counter, and including: pulsegenerating means operative before the beginning of movement of therecording medium along the said path to count up the auxiliary counterand the counting means by a count equal to the said predeterminednumber; gating means operative in response to occurrence of the saidcontrol signal to feed each electrical signal produced by the transducermeans after occurrence of the said control signal into the auxiliarycounter whereby the count down the auxiliary counter; and the secondcontrol means being connected to be controlled by the auxiliary counterand operative to arrest the movement of the recording medium when thepredetermined number in the auxiliary counter has been completelycounted down.
 4. In apparatus having transport mechanism for driving,along a predetermined path, a longitudinally movable recording mediumhaving a plurality of longitudinally arranged areas in whicH informationcan be recorded and a respective marker associated with each area, andtransducer means arranged to produce a respective electrical signal inresponse to the movement of each marker therepast, each electricalsignal comprising first and second time-displaced portions respectivelyproduced by longitudinally-spaced regions of each marker, theimprovement comprising: storage means operative to store an identifyingnumber identifying a particular desired marker which is to bepositioned, by appropriate movement of the recording medium along thesaid path, in a reference position in the path; counting means connectedto the transducer means to count one said portion only of eachelectrical signal produced by the transducer means; comparing meansconnected to the counting means and the storage means and operative tocompare the instantaneous count of the counting means with the saididentifying number in the storage means whereby to produce a controlsignal when the instantaneous count corresponds with the identifyingnumber; control means responsive to the control signal to produce atransport mechanism arresting signal when the particular desired markeris positioned in the said reference position; and gating means connectedto the counting means and operative to feed the first portion only ofeach electrical signal to the counting means, for counting thereby, whenthe recording medium is moving in one direction along the said path andoperative to feed the second portion only of each electrical signal tothe counting means, for counting thereby, when the recording means ismoving in the opposite direction along the said path, whereby the saidone portion of each electrical signal which is counted by the countingmeans is the portion produced by the leading region of each said marker.5. Apparatus according to claim 4, in which the storage means comprisesfirst and second stores, and including: writing means selectivelyconnectable to the first and second stores while the recording medium isstationary and operable to store in the first store a first numberidentifying the particular marker in the said reference position in thesaid path and operable to store in the second store the said identifyingnumber of the particular marker to be positioned, by the appropriatemovement of the recording medium, in the said reference position in thesaid path; and transfer means responsive to the writing means andoperative while the recording medium is stationary to count up thecounting means by a count corresponding with the said first number. 6.Apparatus according to claim 5, including: means operative to add apredetermined number to the count of the counting means so that, as therecording medium moves along the said path, the instantaneous count ofthe counting means is in excess, by the amount of the said predeterminednumber, of the number of electrical signals counted; the said controlmeans comprising first means operative immediately the control signaloccurs to produce a transport mechanism speed reducing signal and secondmeans operative to produce the said transport mechanism arresting signalwhen the number of electrical signals produced by the transducing meansafter occurrence of the said control signal becomes equal to the saidpredetermined number.
 7. In apparatus having variable speed transportmechanism for driving, along a predetermined path, a longitudinallymovable recording medium having a plurality of longitudinally arrangedarea in which information can be recorded and a marker on the mediumadjacent each said area and having different light-transmitting qualityfrom the surrounding medium, and a photocell mounted to produce arespective electrical signal in response to movement of each markertherepast as the recording medium moves along the said path, eachelectrical signal comprising two portions one of which represents alight-to-dark transition in the light falling on the photocell and theOther of which represents a dark-to-light transition; storage meansoperative to store an identifying number identifying a particulardesired marker which is to be positioned, by appropriate movement of therecording medium along the said path, in a reference position in thepath; counting means connected to the transducer means to count one saidportion only of each electrical signal produced by the transducer means;comparing means connected to the counting means and the storage meansand operative to compare the instantaneous count of the counting meanswith the said identifying number in the storage means whereby to producea control signal when the instantaneous count corresponds with theidentifying number; control means responsive to the control signal forproducing a transport mechanism arresting signal when the saidparticular desired marker has been positioned in the said referenceposition; and gating means connected to the counting means and operativeto feed one said portion only of each electrical signal to the countingmeans, for counting thereby, when the recording medium is moving in onedirection along the said path and operative to feed the other saidportion only of each electrical signal to the counting means, forcounting thereby, when the recording medium is moving in the oppositedirection along the said path, whereby the said portion of eachelectrical signal which is counted by the counting means is the portionproduced by the leading edge of each said marker.